The Black Pearl Pepper Banker Plant for Biological Control of Thrips in Commercial Greenhouses

Annual Reports

Commodities

Additional Plants: ornamentals

Practices

Pest Management: biological control

Abstract:

Black Pearl pepper banker plants benefit populations of Orius insidiosus by providing pollen as an alternative source of food compared to a prey-only diet. Laboratory experiments show that adult female survival and size increased, and nymphal development time decreased when pollen from Black Pearl pepper flowers was added to their diet of thrips only. Greenhouse experiments demonstrated that Black Pearl Pepper plants with flowers had higher adult and nymphal abundance than plants that did not have flowers, however in a commercial nursery setting, banker plants failed to enhance biological control by O. insidiosus more than augmentative releases alone.

Introduction

The purpose of this project is to increase adoption of biological control as a sustainable pest management strategy by developing a new banker plant system for thrips management. In doing so, the project aims to reduce insecticide use and risks to workers, other non-target organisms, and the environment.
In North Carolina, ornamental plants are the most valuable crop and yield $22,741 per acre (NCDA 2005). In the United States, ornamental plants are the second most valuable crop worth $14.7 billion (UDSA 2002). Due to the value of ornamental crops, effective and sustainable thrips management is a priority for ornamental growers (IR-4 2007). However, growers are hesitant to implement biological control because current implementation practices, in which growers have to repeatedly purchase and release natural enemies, make it unpredictable and expensive. This project proposes a solution to this problem by using a banker plant system for sustainable management of thrips. In this system, the ‘Black Pearl’ pepper plant, an ornamental pepper that flowers continuously throughout the year, is placed among crop plants to provide pollen for Orius insidiosus, an omnivorous predator of thrips. Preliminary data indicate that ‘Black Pearl’ banker plants can increase and sustain O. insidiosus for multiple generations in a greenhouse which may provide preventative thrips suppression.
Western flower thrips (Frankliniella occidentalis) is distributed worldwide and is the most economically important greenhouse pest of ornamental and vegetable crops. Thrips feeding and oviposition cause aesthetic damage to leaves and fruit tissue in the form of deformed leaves and buds. Thrips also transmit tospoviruses such as Tomato Spotted Wilt Virus and Impatiens Necrotic Spot virus which are lethal to many crops and result in significant economic loss.
To prevent economic loss, growers rely on frequent insecticide applications to reduce thrips abundance and damage. However, thrips are especially hard to control using insecticides because eggs are protected in leaf tissue, pupae are protected in soil, and larvae and adults feed in curled leaves and buds. In addition, rapid evolution of resistance has made many insecticides less effective (Jensen 2000). The difficulty and risks involved in conventional thrips management make development of effective and sustainable alternative management tactics essential.
Biological control can reduce pest abundance and damage to acceptable levels (Vasquez et al. 2006). However, efficacy is unpredictable because natural enemies starve, emigrate from greenhouses, or cannot suppress rapidly increasing pest populations. By providing pollen to sustain O. insidiosus abundance throughout a growing season, banker plant systems could make biological control more effective and affordable. Banker plants systems are also compatible with tactics required to manage pests. They can be moved out of a greenhouse if an insecticide application becomes necessary and replaced after a safe interval to resume thrips suppression by O. insidiosus. Currently no publications describe how to implement the ‘Black Pearl’ banker plant system effectively. Thus, the overall goal of the project is to provide information about this banker plant system to growers who are unlikely to use biological control due to high cost or poor efficacy.

Project objectives:

The overall goal of this project is to develop a banker plant system as a sustainable, effective, and economical management strategy for thrips in greenhouses. To achieve this, the specific objectives are to:

3) Evaluate the efficacy and economics of biological control by O. insidiosus using ‘Black Pearl’ banker plants compared to conventional augmentative releases in commercial greenhouses.

Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.

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